Robert G. Bailey developed a biogeographical classification system for the United States in a map published in 1975. Bailey subsequently expanded the system to include the rest of North America in 1981, and the world in 1989. The Bailey system is based on climate, and is divided into four domains (Polar, Humid Temperate, Dry, and Humid Tropical), with further divisions based on other climate characteristics (subarctic, warm temperate, hot temperate, and subtropical, marine and continental, lowland and mountain).

A team of biologists developed an ecological land classification system for the World Wide Fund for Nature (WWF) that identified 14 biomes, called major habitat types, and further divided the world's land area into 867 terrestrial ecoregions. This classification is used to define the Global 200 list of ecoregions identified by the (WWF) as priorities for conservation. The WWF major habitat types are as follows:

The Endolithic biome, consisting entirely of microscopic life in rock pores and cracks, kilometers beneath the surface, has only recently been discovered and does not fit well into most classification schemes.